The present invention relates to a device for extracting coffee. This device is of the type comprising an extraction chamber to be fed by vertical introduction of tablets or premeasured small quantities of ground coffee.
The invention particularly finds its application in the field of the production and use of machines for the preparation of beverages of the type of espresso coffee. More particularly, the invention relates to machines using tablets or premeasured small quantities of ground coffee.
In this field, there are already known machines permitting the extraction of coffee by simple introduction of small quantities or tablets by the user.
Patent application WO-A-9507041 discloses an espresso coffee machine, comprised conventionally by a boiler and a jack, itself comprised by a cylindrical body enclosing a piston using tablets of coffee or the like. It is constituted by abutments placed at one end of the boiler in a perpendicular position relative to the longitudinal axis of the espresso coffee machine, the jack coacting with said boiler at the level of the abutments to fix in position a coffee tablet or the like which is fixed by its member between the abutments, on the one hand, and the boiler on the other hand.
There is also known from patent application WO-A95/17121 an automatic machine for the preparation of infusions of hot beverages such as coffee, which comprises a group formed by a body placed facing a boiler, adapted to be brought toward each other to form an infusion chamber.
It comprises, between the body and the boiler, at the level of the infusion chamber:
means for receiving an individual package containing the product to be infused, which are constituted by at least one retractable element, extended in substantially lower position, adapted temporarily to immobilize said package between the body and the boiler,
means for holding in position the package which are constituted by two lateral substantially vertical grooves, in which said package slides and is held in vertical position when the receiving means are present, and
automatic ejection means for said package which are constituted by the retractable element which is retracted relative to the passage of the individual package, to permit the ejection by simple gravity of the individual package, the movement of the individual package being perpendicular to the axis of the machine.
There is also known from the document EP-A-0867142 an espresso coffee machine which uses filtering capsules and which has an infusion unit comprising two portions of the infusion chamber which slide relative to each other between an open and a closed position.
These machines, resulting from the work of the applicant, permit using premeasured small quantities or tablets of ground coffee integrated into an extraction chamber (which is to say in which there is carried out the extraction of the coffee). According to the state of the art, the extraction chamber is comprised by two elements movable in horizontal translation so as to move toward or away from each other to open or close the extraction chamber.
Although interesting, such machines do not give complete satisfaction.
In the first place, they have the drawback of being of a relatively complicated design. Thus, they require the use of a system for movement, which is heavy and costly (particularly as to the bias of the jacks). It also requires the use of means adapted to be perfectly adjusted to carry out very precise movements of the two movable portions constituting the chamber.
As a result, the present machines have a size which should be substantially reduced. Moreover, their design is complicated, which leads to high production costs.
The object of the present invention is to overcome such drawbacks by providing a lighter design permitting particularly the mobility of the two elements comprising the extraction chamber without giving rise to the use of heavy and costly movement means.
One of the advantages of the invention is to provide a device using simple drive means comprising a low powered motor and not giving rise to particular problems as to adjustment in position of the movements to be carried out.
Another advantage of the invention is to combine, from a single motor or other drive system, a mobility not only in translation but also in oscillation of the two portions comprising the extraction chamber.
Another object of the device for the extraction of coffee permits more flexibility of use, the replacement or repair of the device. To do this, it has the advantage of comprising easily disassembleable elements such as a screen door or a filter door adapted to be easily replaced.
Another object of the invention is to permit the emplacement and optimum guidance of the tablet or premeasured small quantity of ground coffee during its steps of use.
Other objects and advantages will become apparent from the description which follows, which is however given only by way of example.
The present invention relates to a device for the extraction of coffee, comprising an extraction chamber of the type that is supplied by vertical introduction of tablets or premeasured small quantities of ground coffee, said extraction chamber being comprised of two portions movable horizontally toward and away from each other, one of the movable portions comprising a hot water inlet, the other movable portion being provided with an outlet for coffee extract, characterized by the fact that
the movable portions are each mounted on an eccentric shaft adapted to transmit to them oscillatory movements in opposite directions,
and that it comprises a braked pivot connection between each shaft with an eccentric and each movable portion, so as to combine a horizontal movement and an oscillatory movement for sequencing the phases of opening and closing the extraction chamber.
The device could be made according to particular different modes and particularly those set forth hereafter.
Abutment surfaces on which the movable portions come into bearing, permit limiting the angle of oscillation of it.
Guide means of the tablet are present for maintaining it substantially vertical.
The guide means also constitute the abutment surfaces.
The guide means are formed by two vertical grooved elements to coact with the periphery of the tablet and positioned on opposite sides of the movable portion substantially at the level of their plane of contact.
The pivot connection is braked by a friction shoe carried by each movable portion and bearing resiliently on the periphery of the shaft.
The abutment surfaces give rise to the relative movement of the movable portion and the shaft with an eccentric of the braked pivot connection so as to cause the movable portions to come together when they have reached their maximum angular displacement.
The eccentric shafts are moved by engaging and motor driven toothed wheels, adapted to transmit to the movable portions movements symmetrical relative to their plane of contact.
The movable portions each comprise a movable support mounted on the eccentric shaft and, one has a screen door and the other has a filter door, retractable and mounted on the movable support.
The device comprises at least one position detector adapted to determine the angular position of the toothed wheels.
It comprises at least one detector for the presence of a tablet in loading position.
Starting from a maximum angular position in which the extraction chambers open downwardly, the eccentric shafts carry out an angular movement permitting the opening of the extraction chamber upwardly for the introduction of a tablet, the eccentric shafts pursue their angular movement for closing the extraction chamber, then carry out an angular movement in an opposite direction to bring the extraction chamber to a downwardly open position for discharge of the used tablet and to await the loading of a new tablet.